When he first arrived, the road was a gravel track, as rutted as a washboard. Now it is sealed all the way to the beach to accommodate the constant stream of visitors. "A hundred thousand people a year coming to look at fish—who saw that coming? Nobody," says Ballantine. "Fifteen years ago, if you had suggested that entire school classes would be put into wet suits and taken into the water here you would have been laughed at. Now it's routine."
School field trips by the hundred. Legions of weekend snorkelers. Glass-bottom boat tours for those who prefer to stay dry. A marine education center. None of it was foreseen, either by the university or the nearby fishing and farming community of Leigh, which was split over the idea from the start.
The battle lines were drawn as early as 1965, when Ballantine invited a group of commercial fishermen to the lab and floated his idea for a reserve closed to fishing. "Half of them said, 'No problem,' " he recalls. "The other half said, only half joking, 'We'll kill you.' "
What eventually transformed public opinion were the changes that happened underwater—changes that took everyone, including Ballantine and his fellow scientists, by surprise. Divers at the marine lab had noticed that large swaths of reef in Goat Island Bay were barren, their seaweed communities grazed to a stubble by a type of sea urchin known by its Maori name kina. These underwater lawn mowers, prickly as hedgehogs, had exploded in numbers because their chief predators—snapper and spiny rock lobsters—had been fished down to low levels. Kina even climbed up kelp trunks and gnawed through them, like beavers.
When fishing ceased, the imbalance between predators and prey began reversing almost immediately. Kina numbers dropped. Kelp grew back. Snapper, once wary and rare, became abundant and fearless. Word of this ecological revival soon spread, and the world beat a path to Goat Island's shore.
For reasons not fully understood, when areas are closed to fishing, snapper aggregate within them, forming large resident populations. Spiny rock lobsters ("crayfish" to New Zealanders) do the same. Their density inside the reserve is about 15 times higher than outside. Commercial crayfishermen have cashed in on the reserve's success because the outward migration of crayfish—a process marine biologists call spillover—brings the crustaceans to their pots, strategically placed just outside the boundary. These former skeptics are now some of the reserve's staunchest defenders. They refer to it as "our reserve" and act as marine minutemen, reporting poachers and boundary cheats.
Spillover and larval export—the drifting of millions of eggs and larvae beyond the reserve—have become central concepts of marine conservation. Reserves where fishing is banned are now seen as potential stud farms and fish hatcheries, replenishing the surrounding seas. Research at Goat Island has provided some of the strongest evidence of this replenishment effect—research made possible by the fact that the reserve has been closed to fishing for 30 years.